scispace - formally typeset
Search or ask a question
Proceedings ArticleDOI

Single-phase PQ theory

M.T. Haque1
07 Nov 2002-Vol. 4, pp 1815-1819
TL;DR: The theory of instantaneous reactive power compensation of single-phase circuits is presented in this paper, which is a general case of well-known pq theory and it is usable in single phase as well as three phase circuits.
Abstract: The theory of instantaneous reactive power compensation of single-phase circuits is presented. This theory is a general case of well-known pq theory and it is usable in single-phase as well as three-phase circuits. A new definition of instantaneous active and reactive powers in single-phase circuits that is based on space vector concept is also presented. The principle of operation is explained using analytical analysis. The validity of the presented method and its comparison with original pq theory is studied through simulation results.
Citations
More filters
Journal ArticleDOI
TL;DR: In this article, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults is explored in order to map future challenges, and control strategies with reactive power injection are also discussed.
Abstract: Transformerless photovoltaic (PV) inverters are going to be more widely adopted in order to achieve high efficiency, as the penetration level of PV systems is continuously booming. However, problems may arise in highly PV-integrated distribution systems. For example, a sudden stoppage of all PV systems due to anti-islanding protection may contribute to grid disturbances. Thus, standards featuring with ancillary services for the next-generation PV systems are under a revision in some countries. The future PV systems have to provide a full range of services as what the conventional power plants do, e.g., low-voltage ride-through (LVRT) under grid faults and grid support service. In order to map future challenges, the LVRT capability of three mainstream single-phase transformerless PV inverters under grid faults is explored in this paper. Control strategies with reactive power injection are also discussed. The selected inverters are the full-bridge (FB) inverter with bipolar modulation, the FB inverter with dc bypass, and the Highly Efficient and Reliable Inverter Concept (HERIC). A 1-kW single-phase grid-connected PV system is analyzed to verify the discussions. The tests confirmed that, although the HERIC inverter is the best candidate in terms of efficiency, it is not very particularly feasible in case of a voltage sag. The other two topologies are capable of providing reactive current during LVRT. A benchmarking of those inverters is also provided in this paper, which offers the possibility to select appropriate devices and to further optimize the transformerless system.

307 citations

Journal ArticleDOI
04 Jul 2010
TL;DR: In this article, a single-phase inverter for distributed generation systems requiring power quality features, such as harmonic and reactive power compensation for grid-connected operation, is proposed, where the inverter controls the active power flow from the renewable energy source to the grid and also performs the nonlinear load current harmonic compensation keeping the grid current almost sinusoidal.
Abstract: Power electronic converters are commonly used for interfacing distributed generation systems to the electrical power network. This paper deals with a single-phase inverter for distributed generation systems requiring power quality features, such as harmonic and reactive power compensation for grid-connected operation. The idea is to integrate the DG unit functions with shunt active power filter capabilities. With the proposed approach, the inverter controls the active power flow from the renewable energy source to the grid and also performs the non-linear load current harmonic compensation keeping the grid current almost sinusoidal. The control scheme employs a current reference generator based on Sinusoidal Signal Integrator (SSI) and Instantaneous Reactive Power (IRP) theory together with a repetitive current controller. Experimental results obtained on a 4 kVA inverter prototype demonstrate the feasibility of the proposed solution.

301 citations

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new functionality of UPQC in which both the shunt and series APFs supply the load-reactive power demand, which not only helps to share the load reactive power demand but also helps to reduce the SHunt APF rating.
Abstract: This paper presents a novel philosophy to compensate the load-reactive power demand through a three-phase unified power quality conditioner (UPQC). Most of the UPQC-based applications show the dependency on shunt inverter for load-reactive power compensation, whereas the series inverter is always looked as controlled voltage source to handle all voltage-related problems. This paper proposes a new functionality of UPQC in which both the shunt and series APFs supply the load-reactive power demand. This feature not only helps to share the load-reactive power demand, but also helps to reduce the shunt APF rating, and hence, the overall cost of UPQC. This results in better utilization of the existing series inverter. The theory and complete mathematical analysis termed as ldquopower angle control (PAC)rdquo is presented. The simulation results based on MATLAB/Simulink are discussed in detail to support the concept developed in the paper. The proposed approach is also validated through experimental study.

216 citations

Journal ArticleDOI
TL;DR: In this paper, a novel structure for a three-phase four-wire (3P4W) distribution system utilizing unified power quality conditioner (UPQC) is presented.
Abstract: This paper presents a novel structure for a three-phase four-wire (3P4W) distribution system utilizing unified power quality conditioner (UPQC). The 3P4W system is realized from a three-phase three-wire system where the neutral of series transformer used in series part UPQC is considered as the fourth wire for the 3P4W system. A new control strategy to balance the unbalanced load currents is also presented in this paper. The neutral current that may flow toward transformer neutral point is compensated by using a four-leg voltage source inverter topology for shunt part. Thus, the series transformer neutral will be at virtual zero potential during all operating conditions. The simulation results based on MATLAB/Simulink are presented to show the effectiveness of the proposed UPQC-based 3P4W distribution system.

177 citations


Cites background from "Single-phase PQ theory"

  • ...At the same time, the switching operation of these devices generates current harmonics resulting in a polluted distribution system....

    [...]

Journal ArticleDOI
TL;DR: In this article, a comprehensive review of neutral current compensation methods, their topologies, and their technical and economical limitations is presented, and simulations are also carried out in MATLAB/SIMULINK environment for comparing the existing methods.

95 citations

References
More filters
Journal ArticleDOI
TL;DR: In this paper, a new instantaneous reactive power compensator comprising switching devices is proposed, which requires practically no energy storage components, and is based on the instantaneous value concept for arbitrary voltage and current waveforms.
Abstract: The conventional reactive power in single-phase or three- phase circuits has been defined on the basis of the average value concept for sinusoidal voltage and current waveforms in steady states. The instantaneous reactive power in three-phase circuits is defined on the basis of the instantaneous value concept for arbitrary voltage and current waveforms, including transient states. A new instantaneous reactive power compensator comprising switching devices is proposed which requires practically no energy storage components.

3,331 citations

Journal ArticleDOI
TL;DR: In this paper, a generalized theory of instantaneous reactive power for three-phase power systems is proposed, which is valid for sinusoidal or nonsinusoidal, balanced or unbalanced, three phase power systems with or without zero-sequence currents and/or voltages.
Abstract: A generalized theory of instantaneous reactive power for three-phase power systems is proposed in this paper. This theory gives a generalized definition of instantaneous reactive power, which is valid for sinusoidal or nonsinusoidal, balanced or unbalanced, three-phase power systems with or without zero-sequence currents and/or voltages. The properties and physical meanings of the newly defined instantaneous reactive power are discussed in detail. A three-phase harmonic distorted power system with zero-sequence components is then used as an example to show reactive power measurement and compensation using the proposed theory.

755 citations

Journal ArticleDOI
TL;DR: In this article, a different interpretation of the power decomposition proposed by H. Akagi et al. for distorted three-phase situations is given, which makes it possible to generalize the technique to single-phase systems and polyphase systems, also to include rigorously zero sequence currents and voltages.
Abstract: A different interpretation of the power decomposition proposed by H. Akagi et al. (1984) for distorted three-phase situations is given. This makes it possible to generalize the technique to single-phase systems and polyphase systems and also to include rigorously zero sequence currents and voltages. >

265 citations

Journal ArticleDOI
TL;DR: In this article, a control algorithm for the performance improvement of three-phase threewired active power filters under non-ideal mains voltages is proposed and analyzed, and the proposed algorithm has been implemented as a prototype.
Abstract: In this paper, a control algorithm for the performance improvement of three-phase three-wired active power filters under nonideal mains voltages is proposed and analyzed. It begins with an analysis of an instantaneous reactive power algorithm that was previously applied to the three-phase active power filter design. In that design, the circuit performance was found unsatisfactory under nonideal test scenarios. Our proposed design was, therefore, motivated in order to solve such problems. In the proposed scheme, not only was the control circuit simplified, but it also served as a potential candidate for the performance improvement of active filter design. The proposed algorithm has been implemented as a prototype. Results of experimental verification under various scenarios are presented.

124 citations

Proceedings ArticleDOI
03 Aug 1997
TL;DR: In this article, the authors proposed a calculation method for the compensating current reference of an active power filter, where a nonlinear load exists in the three-phase three-wire unsymmetrical voltage system.
Abstract: In this paper, the authors propose a calculation method for the compensating current reference of an active power filter, where a nonlinear load exists in the three-phase three-wire unsymmetrical voltage system. This new method has been named the extension pq method. The authors have experimented with the extension pq method and the pq method, using the same current controlled IPM inverter for both methods. The results of the experiments proved that, in an unsymmetrical voltage system, the source current was distorted in the case of the pq method, but undistorted in the case of the extension pq methods. Finally, the authors propose calculation methods for the compensating current reference in an unsymmetrical and distorted line voltage system. Experimental results show that the active power filter based on this method gives satisfactory operation.

35 citations